It's just an anomaly caused by a badly calibrated radar.
It's set 'too sensitive' so is picking up echoes that aren't actually precipitation.
You can sometimes observe virga (very light rain that evaporates before reaching the ground' but i'd say by the looks of your image that the radar hardware just needs some maintenance.
https://ausradaranomalies.wordpress.com/radar-anomalies-and-corresponding-stations/